This invention relates to a drilling fixture and, more particularly, to a drilling fixture for the accurate positioning of drill bits and control of the direction and course of the drill bits during drilling of cylindrical-shaped workpieces either on or off center.
Prior workers in the art have addressed the problem of drilling cylindrical-shaped workpieces. As is known in the art, the problems with drilling cylindrical-shaped workpieces reside in locating the drill precisely at the spot to be drilled and then maintaining the direction and course of the drill during the drilling operation. In drilling cylindrical-shaped workpieces, the drill tends to wander on the cylindrical surface when drilling is started; and, once drilling has begun, it is difficult to keep the drill bit in proper alignment which results in sticking of the drill in the drill hole and possible breaking of the drill. Representative of prior art drill fixtures for the drilling of cylindrical workpieces are U.S. Pat. Nos. 550,767, 907,735, 1,329,970, 2,208,480, 3,138,975, and 4,005,945. These patents all involve some sort of fixture for holding the workpiece in place as well as some form of drill guide. The problem with the prior art, however, is that the drill fixtures typically are made up of relatively complicated mechanisms for holding the workpiece and centering the drill and/or lack both an efficient design and versatility. These prior fixtures thus lack compactness and economies of manufacture as well as the versatility to drill different size and shape workpieces with drill bits of various diameters either on or off center.